The present invention relates to multi-dimensional optical spectrometers and in particular to a multi-dimensional optical spectrometer suitable for measurements over large frequency ranges.
Multi dimensional spectroscopy can reveal the interaction between coupled systems of atoms and/or molecules. For example, two-dimensional spectroscopy may provide an intuitively understandable two-dimensional spectrum in which the emission frequency of the system is plotted against the original excitation frequency. In a 2D spectrum, electromagnetic transitions of atoms or molecules matching the incident light give rise to signals that lie on the spectrum diagonal, but if there are interactions between transitions within or among molecules, then cross peaks will also appear in the spectrum. The diagonal and cross peaks can be used to deduce molecular structures or identify mixtures of compounds, etc. Multidimensional spectra of 3D or higher provide additional information.
To collect multidimensional spectrum, one needs to generate multiple light pulses to interrogate the sample. Typically a set of probe pulses are used to excite the sample which is then interrogated by a probe pulse. Some examples of two-dimensional spectroscopy are described in US patent application 2006/0063188 filed Sep. 15, 2005; US patent application 2009/0161092 filed Dec. 21, 2007; and US patent application 2012/0236305 filed Sep. 20, 2012, all hereby incorporated by reference.
Processes related to photosynthesis or solar energy, among others, could benefit from multidimensional spectrographic analysis; however, such analysis is challenging because of the large spectral range that must be analyzed, a range that can extend across the entire visible and near infrared wavelength region. Tuning the frequency of pump pulses over a large spectral bandwidth while preserving the necessary frequency and phase accuracy is difficult.